FR2748015A1 - APPARATUS AND METHOD FOR MANUFACTURING METAL-COATED OPTICAL FIBER - Google Patents

Abstract

The apparatus comprises a crucible (12) for melting the optical fiber preform (10) in order to draw an uncoated optical fiber (14), a diameter measuring device (16) for measuring the diameter of the non-optical fiber coated (14) to regulate this diameter, a metallic coating device (18) for coating the uncoated optical fiber with metal to prevent the ingress of moisture, a temperature controller (22) for controlling the interior temperature of the metallic coating device (18), a cooling device (26) for cooling the metallized optical fiber (30) at high temperature, a capstan (32) for drawing the optical fiber from the optical fiber preform (10) by applying a rotational force, and a coil (34) for winding the metallized optical fiber.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention

  The present invention relates to an apparatus and method for manufacturing a metal coated optical fiber.

  2. Description of the technique concerned

  In general, the silica optical fiber used for communications has a diameter of about micrometers to 150 micrometers, and this fiber is therefore covered with a reinforcing coating to prevent inadvertent fracture. In addition, a concentrated constraint

  at the site of a slight defect causes a fracture of the

  bre optics. Theoretically, the optical fiber in silica pre-

  feels a high resistance, greater than 14 GPa but, if it is brought into contact with moisture, the optical fiber becomes very fragile. As a result, the optical fiber is covered with a reinforcing coating made of a suitable material, so as to protect the surface of the optical fiber, to reinforce the tensile and bending resistance, and to prevent the ingress of moisture. 20 Figure 1 is a diagram intended to illustrate a

  conventional apparatus for manufacturing an optic fiber

  coated with ultra-light cured plastic resin

  violet. The apparatus includes a crucible 52 for melting

  the optical fiber preform 50 in order to draw an optical fiber

  uncoated 54, a diameter measuring device 56

  to continuously measure the diameter of the optic fiber

  that uncoated 54 in order to keep this diameter constant, a

  cooling device 58 arranged below the arrangement

  diameter measurement device to cool the optic fiber

  than uncoated 54 from its high temperature to the

  room temperature, a coating device 60 for

  cover the uncoated optical fiber with a coating of

  acrylic or silicone resin hardened by ultraviolet light, to protect the fiber from the environment

  outside, a hardening device 62 disposed above

  below the coating device 60 for hardening the coated optical fiber 64, a capstan 66 for pulling the fiber

  optical from the optical fiber preform 50 in application

  as for a rotational driving force, and a coil 68

  for winding the coated optical fiber 64.

  During operation, the optical fiber preform 50 slowly feeds the crucible 52 under the control of a preform position control mechanism (not shown

  present). We operate the crucible 52 at several mil-

  liers of degrees C, typically 2100 to 2200 C. The fiber

  uncoated optic 54 is pulled from the dry portion

  reduced transverse tion of the optical fiber preform 50.

  The pulling force is generated by the capstan 66.

  The diameter measuring device 56 performs a measurement of the diameter of the uncoated optical fiber 54

  to generate a measurement signal which is transferred to a controller

  diameter reader (not shown) intended to regulate the diameter

  meter to a specified dimension of eg micrometers. Thus, the diameter regulator controls the

  tensile force of capstan 66 in response to the signal

  safe; so as to maintain the diameter of the uncoated optical fiber 54 at 125 micrometers. After having been rapidly cooled by the cooling device 58, the uncoated optical fiber 54 is covered by the

  coating 60, of an acrylic or silicon resin coating

  cone serving as a protective coating. The optical fiber

  coated 54 is cured by the curing device. In-

  end, the coated optical fiber 64 is wound around the

coil 68.

  This conventionally manufactured otic fiber

  coated with a resin hardened in ultraviolet light

  lette, is very sensitive to the humidity contained in

  the atmosphere, so that moisture entering the coating

  Resin degrades the resistance of optical fiber 64, even at low impact, easily destroying the

  fiber. In addition, such a resin cannot withstand a temperature

  high erection above 200 C, so that it is difficult

  It is also possible to use such a conventional optical fiber 64 in a high temperature environment.

at high humidity.

Summary of the invention

  The object of the present invention is to create a

  optical bre with a coating material intended to prevent

  expensive that the optical fiber is damaged even in a high temperature and high humidity environment. Another object of the present invention is to

  create an optical fiber reinforced by a metallic coating

  than. Yet another object of the present invention is

  to create a manufacturing process for a metal optical fiber

  read. Yet another object of the present invention is

  create a process to prevent moisture from entering

  be in an optical fiber in the presence of an environment

  high temperature and high humidity.

  Yet another object of the present invention is

  to create a process for continuously covering a

  optical bre by a coating of conductive metal.

  Yet another object of the present invention is

  to create an apparatus and a method for drawing an optic fiber

  only to be coated with metal.

  Yet another object of the present invention is

  to create a metallized optical fiber to be welded di-

  directly to a metal panel.

  To this end, the present invention relates to an apparatus for manufacturing an optical fiber coated with metal, characterized in that it comprises: * a crucible for melting the optical fiber preform in order to draw an uncoated optical fiber;

  has a diameter measuring device to measure the diameter

  to be uncoated optical fiber in order to regulate this diameter

  metre; * a metal coating device for covering with

  metal layer the uncoated optical fiber, to prevent

  expensive moisture penetration; * a temperature controller to control the interior temperature of the metal coating device; * a cooling device for cooling the metallized optical fiber at high temperature;

  * a capstan to pull the optical fiber from the pre-

  form of optical fiber by applying a driving force

ment in rotation; and

  * a coil to wind the metallized optical fiber.

  The metallized optical fiber comprises a light transmitting core, a coating formed on the core and having a lower refractive index than that of the core, and a metal coating layer formed on the

  core coating to prevent ingress of moisture.

  According to other characteristics of the apparatus according to the invention:

  * it also includes a thermoelectric torque for measurement

  rer the temperature of the molten metal in the device

  metallic coating in order to transfer the measurement to the

  temperature monitor to control the indoor temperature

  lower of the metal coating device, * a cooling gas supply device is mounted on one side of the bottom of the cooling device in order to provide a supply of inert gas serving as refrigerant for this cooling device,

  * the inert gas can be He, Ar or N ,.

  * it also includes an auxiliary cooling device

  binder placed between the diameter measuring device and the metal coating device to cool the uncoated optical fiber to room temperature

  before it enters the metallic coating device

  metal, * it also includes a table to move the device

  metallic coating to properly align the

  uncoated optical bre in the center of the coating device

metallic.

  The invention also relates to a metallized optical fiber, made of silica as the main component, characterized in that: * it comprises a light-transmitting core, a coating formed on the core and having an index of

  refraction lower than that of the nucleus, and a layer of

  tal formed on the coating to prevent the penetration of moisture, * the thickness of the metal layer is between 5 micrometers and 50 micrometers, * the optical fiber can be a single mode optical fiber, an optical fiber with diffusion propagation, an optical fiber

  multimode, an optical fiber with erbium added, a

  diffusion-compensated optical bre, or an optic fiber

  that at polarization, * it comprises a light transmitting core, a coating formed on the core and having a refractive index lower than that of the core, and a layer of

  copper formed on the coating to prevent penetration

  moisture content, * the thickness of the copper layer is between micrometers and 50 micrometers, * it includes a light-transmitting core, a coating formed on the core and having a refractive index lower than that of the core , and a layer

  of tin formed on the coating to prevent penetration

  humidity, * the thickness of the tin layer is between micrometers and 50 micrometers, * it includes a light-transmitting core, a coating formed on the core and having an index of

  refraction lower than that of the nucleus, and a layer of aluminum

  minium formed on the coating to prevent penetration

  humidity, * the thickness of the aluminum layer is between micrometers and 50 micrometers. According to another aspect of the invention, it

  relates to a process for manufacturing a metal optical fiber

  border made of silica or silica with added

  pant, characterized in that it comprises the steps consisting of * drawing an uncoated optical fiber from a preform of optical fiber made of fused silica in a crucible, * regulating the diameter of the uncoated optical fiber for

  that it has a given dimension, by means of a provision

diameter measurement device,

  * pass the uncoated optical fiber through a device

  positive of metallic coating containing a molten metal, to form a layer of metal of given thickness on the uncoated optical fiber, * cooling the metallized optical fiber in a cooling device, and

  * wind the metallized optical fiber, using a cabes-

tan, around a coil.

  According to other characteristics of the process,

  according to the invention: * the thickness of the metal layer is determined by the temperature of the molten metal and by the drawing speed of the optical fiber, * the time during which the uncoated optical fiber remains in contact with the metal molten in the metal coating device, is in the range from 0.001 sec to 0.1 sec, * it includes the steps of:

  - pull an uncoated optical fiber from a pre-

  form of optical fiber made of silica melted in a crucible, - regulate the diameter of the uncoated optical fiber so that it has a given dimension, by means of a diameter measuring device, - pass the uncoated optical fiber through a metallic coating device containing molten copper, so as to form a layer of copper of given thickness on the uncoated optical fiber,

  - cool the copper coated optical fiber in a dis-

  positive cooling, and - wind the copper coated optical fiber, by means of a capstan, around a coil, * the temperature of the molten copper in the metal coating device is in the range of 1083 C at

1110 C,

  * it includes the steps of:

  - pull an uncoated optical fiber from a pre-

  form of optical fiber made of silica melted in a crucible, - regulate the diameter of the uncoated optical fiber to

  that it has a given dimension, by means of a dis-

  diameter measurement positive, - passing the uncoated optical fiber through a metal coating device containing molten tin, so as to form a layer of tin of given thickness on the uncoated optical fiber,

  - cool the optical fiber coated with tin in a dispo-

  cooling device, and - wind the tin-coated optical fiber, by means of a capstan, around a coil, * the temperature of the molten tin in the metal coating device is in the range of 231 C to

260 C,

  * it includes the steps of:

  - pull an uncoated optical fiber from a pre-

  form of optical fiber made of silica melted in a crucible, - regulate the diameter of the uncoated optical fiber to

  that it has a given dimension, by means of a dis-

  diameter measurement positive, - pass the uncoated optical fiber through a

  metallic coating device containing aluminum

  molten nium, so as to form a layer of aluminum

  nium of given thickness on the uncoated optical fiber, - cooling the aluminum coated optical fiber in a cooling device, and - winding the aluminum coated optical fiber, by means of a capstan, around a coil , * the temperature of the molten aluminum in the metal coating device is in the range of 660 C to 6900C

Brief description of the drawings

  The present invention will be described below from

  in more detail using embodiments re-

  shown in the accompanying drawings in which: * Figure 1 is a diagram intended to illustrate the apparatus

  conventional for the manufacture of a coated optical fiber

  kills with plastic resin; * Figure 2 is a diagram intended to illustrate the apparatus according to the invention for manufacturing a metallized optical fiber; * Figure 3A is a cross-sectional view of an optical fiber coated with a layer of copper, according to the present invention; * Figure 3B is a view similar to that of Figure 3A, but with a layer of tin; and * Figure 3C is a view similar to that of Figures 3A and

  3B, but with a layer of aluminum.

  Detailed description of the preferred embodiment

  Referring to Figure 2, an apparatus for

  bricating of an optical fiber coated with a metal layer, comprises a crucible 12 for melting the optical fiber preform 10 at a high temperature of 2150 C, so as to

  pull an uncoated optical fiber 14, a measuring device

  diameter 16 gauge for continuous measurement of the diameter

  tre uncoated optical fiber in order to regulate this diameter, and a metallic coating device 18 for covering the uncoated optical fiber 14 with a layer of copper 40, tin 42 or aluminum 44 under a thickness of

  5 micrometers to 50 micrometers, so as to prevent

  humidity. Figures 3A, 3B and 3C illustrate the

  cross section of respective coated optical fibers

ment of Cu, Sn and Al.

  An auxiliary cooling device can be provided between the diameter measuring device 16 and the

  metal coating device 18 for cooling the film

  uncoated optical bre 14 at room temperature 25 C

  before it enters the metal coating device-

  lique 18. The metallic coating device 18 is provided

  of a thermoelectric couple 20 intended to measure the temperature

  ture of molten metal to transfer the measurement signal to a temperature controller 22 which controls the internal temperature of the metal coating device 18 in order to

  keep the molten metal at a constant temperature. A table 24 is also used to move the metallic coating device 18 in order to align cor-

  the uncoated optical fiber 14 in the center of the metallic coating device. A cooling device 26 is placed below the table 24 to cool the metallized optical fiber 30 at high temperature. A cooling gas supply device 28 is mounted on one side of the bottom of the cooling device 26 to supply an inert gas such as He, Ar and N serving as refrigerant to the cooling device 26. A capstan 32 is used to pull the optical fiber from the optical fiber preform 10 by applying a rotational driving force. Finally, a coil 34

  is used to wind the metallized optical fiber 30.

  In the description of the process according to the invention for manufacturing an optical fiber coated with copper according to a

  first embodiment of the present invention, the optical fiber preform 10 made of silica or of silica added with a dopant, is introduced slowly into the

  crucible 12 under the control of a po-

  preform sition (not shown). The crucible 12 is made to operate at several thousand degrees C, typically 2100 to 2200 C. The uncoated optical fiber 14 is drawn from the reduced cross section of the preform of

  fiber optic 10. The pulling force is generated by the

bestan 32.

  The diameter measuring device 16 performs a measurement of the diameter of the uncoated optical fiber 14 to generate a measurement signal transferred to a light regulator.

  diameter (not shown) to regulate the diameter to a di-

  specified mension of for example 125 micrometers. So the

  diameter regulator controls the pulling force of the cabes-

  tan 32 in response to the measurement signal so as to maintain the diameter of the uncoated optical fiber 14 at 125 micrometers. After passage through the measuring device

  of diameter 16, the uncoated optical fiber 14 is covered

  copper green 40 under a constant thickness in the dis-

  metal coating positive 18 containing 99.9% purity molten copper. The thickness of the copper layer on the uncoated optical fiber 14 is determined by the temperature of the molten copper 40 and the drawing speed of the optical fiber. Specifically, the surface temperature

  uncoated optical fiber 14 passing through the dis-

  positive of metallic coating 18 is about 25 C, and the

  temperature of the molten copper 40 in the reflector

  metallic garment 18 is greater than 1085 C. Consequently, when the cold surface of the uncoated optical fiber 14

  comes into contact with molten copper 40 at high temperature

  ture, the molten copper 40 adjacent to the uncoated optical fiber 14 is fixed thereto by solidification. In this case, if the time during which the uncoated otic fiber 14 is in contact with the molten copper is extended, the surface temperature of the uncoated optical fiber 14 is increased by the transfer of heat from the copper. in fusion 40, so that the volume of copper 40 solidified on the uncoated optical fiber 14 is gradually reduced in

  thus also reducing the thickness of the copper layer.

  Therefore, to obtain a suitable thickness of the copper layer, it is preferable that the time during which the uncoated optical fiber 14 remains in contact with the molten copper 40, is in the range of 0.001 sec to 0.1 dry

  and, better still, between 0.001 sec and 0.4 sec.

  Finally, the optical fiber 30 coated with copper 40 is cooled slowly by the cooling device 26, then wound around the coil 34 under the control of

  the pulling force of capstan 32. Thus, the otic fiber makes

  brick 30 consists of a light transmission core 36

  mière, a coating 38 formed on the core and having a

  refractive index lower than that of the nucleus, and a

  40 micrometer thick copper reinforcement 40

  sor formed on the coating to prevent penetration

  humidity. The copper layer can be formed on a fi-

  single mode optical bre, on a diffusion propagation optical fiber, on a multimode optical fiber, on an optical fiber with erbium added, on a diffusion compensated optical fiber, or on a polarization optical fiber.5 The copper layer formed on the optical fiber

  completely prevents moisture penetration and therefore

  that the degradation of the resistance of the optical fiber, and

  allows optical fiber not only to transmit light

  the nucleus but still to transmit an electrical signal

  tackled by the copper layer, so that the fiber is economical. In addition, copper-coated optical fiber can be used without being damaged in a harsh environment.

  temperature above 200 C, and begins to have a re-

  enhanced curvature resistance and extended service life

  which improves reliability.

  In the description of the process according to the invention

  to manufacture an optical fiber coated with tin according to a second embodiment of the present invention, the optical fiber preform 10, made of silica or of silica added with a dopant, is introduced slowly into the

  crucible 12 under the control of a po-

  preform sition (not shown). The crucible 12 is made to operate at several thousand degrees C, typically 2100 to 2200 C. The uncoated optical fiber 14 is drawn from the reduced cross section of the preform of

  fiber optic 10. The pulling force is generated by the

bestan 32.

  The diameter measuring device 16 performs a measurement of the diameter of the uncoated optical fiber 14 to generate a measurement signal transferred to a light regulator.

  diameter (not shown) to regulate the diameter to a di-

  specified mension of for example 125 micrometers. So the

  diameter regulator controls the pulling force of the cabes-

  tan 32 in response to the measurement signal, so as to maintain the diameter of the uncoated optical fiber 14 at 125 micrometers. After passing through the measuring device

  of diameter 16, the uncoated optical fiber 14 is covered

  green with a layer of tin 42 of constant thickness, in the metal coating device 18 containing molten tin at 99.9% purity. The thickness of the tin layer on the uncoated optical fiber 14 is determined by the temperature of the molten tin 42 and the drawing speed of the optical fiber. Specifically, the temperature

  surface of the uncoated optical fiber 14 passing through

  towards the metal coating device 18 is approximately

   C, and the temperature of the molten tin 42 in the dis-

  positive of metallic coating 18 is about 235 C. By

  later, when the cold surface of the optical fiber not re-

  clothed 14 comes into contact with molten tin 42 at high temperature, molten tin 42 adjacent to the uncoated optical fiber 14 is fixed thereto by solidification. In this

  case, if we extend the time during which the fiber opti-

  that uncoated 14 is in contact with the molten tin, the surface temperature of the uncoated optical fiber 14 is increased by the transfer of heat from the molten tin 42, so that the volume of the tin 42 solidified on the optical fiber 14 is gradually reduced, thereby also reducing the layer of tin. Consequently, in order to obtain a suitable thickness of the tin layer, it is preferable that the time during which the uncoated optical fiber 14 remains in contact with the molten tin 42, be within the

range from 0.001 sec to 0.1 sec.

  Finally, the optical fiber 30 coated with tin 42 is cooled slowly by the cooling device 26, then wound around the coil 34 under the control of the

  pulling force of the capstan 32. Thus, the otic fiber 30 fa-

  brick consists of a light transmission core 36, a coating 38 formed on the core and having a lower refractive index than that of the core, and a layer of reinforcing tin 42 22 micrometers thick. formed on the coating to prevent the ingress of moisture. The tin layer can be formed on a fiber

  single mode optics, on a diffuse propagation optical fiber

  fusion, on a multimode optical fiber, on an optical fiber

  added with erbium, on an optical fiber with

  diffusion compensation, or on a polar polarized fiber

  station. The layer of tin formed on the optical fiber completely prevents the penetration of moisture and therefore

  that degrade the resistance of the optical fiber. In addition, tin coated optical fiber can be used,

  without being damaged, in an environment with a temperature above 100 ° C., and begins to have increased resistance to curvature and an extended service life, which improves reliability.

  Similarly, in the description of the method according to the invention for manufacturing a coated optical fiber

  of a layer of aluminum, according to a third embodiment of the present invention, the optical fiber preform 15 10 made of silica or of silica added with a dopant, is introduced slowly into the crucible 12 under the control

  a preform position control mechanism (not shown

  present). We operate the crucible 12 at several mil-

  liers of degrees C, typically 2100 to 2200 C. The fiber

* uncoated optic 14 is drawn from the dry part-

  reduced transverse tion of the optical fiber preform 10.

  The pulling force is generated by the capstan 32.

  The diameter measuring device 16 performs a measurement of the diameter of the uncoated optical fiber 14 to generate a measurement signal transferred to a light regulator.

  diameter (not shown) to regulate the diameter to a di-

  specified mension of for example 125 micrometers. So the

  diameter regulator controls the pulling force of the cabes-

  tan 32 in response to the measurement signal, so as to maintain the diameter of the uncoated optical fiber 14 at 125 micrometers. After passing through the measuring device

  of diameter 16, the uncoated optical fiber 14 is covered with a layer of aluminum 44 of constant thickness, in the

  metallic coating device 18 containing molten aluminum at 99.9% purity. The thickness of the layer

  of aluminum on the uncoated optical fiber 14 is determined

  born by the temperature of molten aluminum 44 and the vi-

  fiber optic drawing size. More specifically, the surface temperature of the uncoated optical fiber 14 passing through the metallic coating device 18

  is about 25 C, and the temperature of aluminum in fu-

  sion 44 in the metallic coating device 18 is approximately 660 C. Thus, when the cold surface of the uncoated optical fiber 14 comes into contact with the aluminum

  high-temperature melting 44, molten aluminum 44 already

  one hundred to the uncoated optical fiber 14 attaches to it by

  solidification. In this case, if you extend the time for

  in which the uncoated otic fiber 14 is in contact with the molten aluminum, the surface temperature of the uncoated optical fiber 14 is increased by the transfer of heat from the molten aluminum 44, so that the The volume of aluminum 44 solidified on the optical fiber 14 is gradually reduced, thereby also reducing the thickness of the aluminum layer. Consequently, to obtain a suitable thickness of the aluminum layer, it is preferable that the time during which the uncoated optical fiber 14 remains in contact with the molten aluminum 44, is

  is in the range of 0.001 sec to 0.1 sec.

  Finally, the optical fiber 30 coated with aluminum 44 is cooled slowly by the cooling device 26, then wound around the coil 34 under the control of the drawing force of the capstan 32. Thus, the optical fiber 30

  manufactured consists of a light transmission core 36

  mière, a coating 38 formed on the core and having a

  refractive index lower than that of the nucleus, and a

  aluminum reinforcement 44 22 micrometers thick

  formed on the coating to prevent the ingress of moisture. The aluminum layer can be formed on a single mode optical fiber, on a diffusion propagation optical fiber, on a multimode optical fiber, on a fiber.

  optical supplemented with erbium, on an optical fiber with compensation

  diffusion station, or on a polarized optical fiber.

  The aluminum layer formed on the optical fiber

  completely prevents moisture penetration and therefore

  that degrade the resistance of the optical fiber. Of

  In addition, aluminum coated optical fiber can be used.

  seated, without being damaged, in an environment with a temperature higher than 200 ° C., and begins to have an increased resistance to bending and an extended service life, which improves reliability.

Claims (18)

R E V E N D I C A T IONS   1) Apparatus for manufacturing an optical fiber coated with metal, characterized in that it comprises:   * a crucible (12) to melt the preform of op-   tick (10) to pull an uncoated optical fiber (14); * a diameter measuring device (16) for measuring the   diameter of the uncoated optical fiber (14) in order to regulate   this diameter; * a metallic coating device (18) for covering the uncoated optical fiber (14) with a layer of metal, in order to prevent the ingress of moisture;   * a temperature controller (22) to control the temperature   internal scratching of the metallic coating device (18);   * a cooling device (26) for cooling the fi   metallized optical bre (30) being at high temperature   ture; * a capstan (32) for pulling the optical fiber from the optical fiber preform (10) by applying a rotational driving force; and * a coil (34) for winding the metallized optical fiber (30).   2) Apparatus for manufacturing an optical fiber according to the re-   vendication 1, characterized in that   it further comprises a thermoelectric couple (20) for me-   monitor the temperature of the molten metal in the metal coating device (18) in order to transfer the measurement to the temperature controller (22) to control the interior temperature of the metal coating device (18)   3) Apparatus for manufacturing an optical fiber according to the re-   Vendication 1, characterized in that a cooling gas supply device (28) is mounted on one side of the bottom of the cooling device (26) in order to provide an inert gas supply serving   refrigerant for this cooling device (26).   4) Apparatus for manufacturing an optical fiber according to the re-   vendication 3, characterized in that the inert gas can be He, Ar or N.) Apparatus for manufacturing an optical fiber according to claim 1, characterized in that   it also includes an auxiliary cooling device   bond placed between the diameter measuring device (16) and the metal coating device (18) to cool   the uncoated optical fiber (14) up to the am-   biante before it enters the metal coating device (18)   6) Apparatus for manufacturing an optical fiber according to the re-   vendication 1, characterized in that   it further comprises a table (24) for moving the device   metal coating (18) to properly align the uncoated optical fiber (14) in the center of the metallic coating (18).   7) Metallized fiber made of silica as the main component   cipal, characterized in that it comprises a core (36) for transmitting light, a   coating (38) formed on the core (36) and having an in-   refractive dice lower than that of the core, and a metal layer (40, 42, 44) formed on the coating (38) to   catch moisture penetration.   8) Metallized optical fiber according to claim 7, characterized in that the thickness of the metal layer (40, 42, 44) is between micrometers and 50 micrometers. 9) Metallized optical fiber according to claim 7, characterized in that the optical fiber can be a single mode optical fiber, a diffusion propagation optical fiber, a multimode optical fiber, an optical fiber with erbium added, a compensation optical fiber of diffusion, or a polarized optical fiber.    ) Metallized optical fiber made of silica as a component   main health, characterized in that it comprises a core (36) for transmitting light, a   coating (38) formed on the core (36) and having an in-   dice of refraction lower than that of the core, and a copper layer (40) formed on the coating (38) to prevent the moisture penetration.   11) Metallized optical fiber according to claim 10, characterized in that the thickness of the copper layer (40) is between 5 micrometers and 50 micrometers.   12) Metallized optical fiber made of silica as a component   main health, characterized in that it comprises a core (36) for transmitting light, a   coating (38) formed on the core (36) and having an in-   dice of refraction lower than that of the core, and a layer of tin (42) formed on the coating (38) to prevent the moisture penetration.   13) Metallized optical fiber according to claim 12, characterized in that the thickness of the tin layer (42) is between micrometers and 50 micrometers.   14) Metallized optical fiber made of silica as a component   main health, characterized in that it comprises a core (36) for transmitting light, a coating (38) formed on the core and having an index of   refraction lower than that of the nucleus, and a layer of aluminum   nium (44) formed on the coating (38) to prevent humidity.    ) Metallized optical fiber according to claim 14, characterized in that the thickness of the aluminum layer (44) is between micrometers and 50 micrometers. 16) Method for manufacturing a metallized optical fiber made of silica or of silica added with a dopant, characterized in that it comprises the steps consisting in: * drawing an uncoated optical fiber (14) from a optical fiber preform (10) of silica melted in a crucible (12), * regulating the diameter of the uncoated optical fiber (14) so that it has a given dimension, by means of a diameter measuring device, * passing the uncoated optical fiber (14) through a metal coating device (18) containing a molten metal, to form a metal layer (40, 42, 44) of given thickness on the uncoated optical fiber (14), * cooling the metallized optical fiber in a cooling device (26), and   * wind the metallized optical fiber, using a cabes- tan (32), around a coil (34).   17) A method of manufacturing a metallized optical fiber according to claim 16, characterized in that the thickness of the metal layer (40, 42, 44) is determined by the temperature of the molten metal and by the speed of fiber optic printing.   18) A method of manufacturing a metallized optical fiber according to claim 16, characterized in that, the time during which the uncoated optical fiber (14) remains in contact with the molten metal in the metallic coating device (18) , is in the range of 0.001 sec to 0.1 sec.   19) Method for manufacturing a metallized optical fiber made of silica or of silica added with a dopant, characterized in that it comprises the steps consisting in: * drawing an uncoated optical fiber (14) from a optical fiber preform (10) made of silica melted in a crucible (12), * regulate the diameter of the uncoated optical fiber (14) so that it has a given dimension, by means of a diameter measuring device (16), * pass the uncoated optical fiber (14) through a   metallic coating device (18) containing copper   vre in fusion, so as to form a copper layer (40) of given thickness on the uncoated optical fiber (14),   * cool the optical fiber coated with copper in a dispo-   cooling device (26), and * wind the copper-coated optical fiber (30), using   a capstan (32), around a spool (34).    ) Method for manufacturing a metallized optical fiber according to claim 19, characterized in that   the temperature of the molten copper in the reflector   metallic clothing (18) is in the range of 1083 C to 1110 C.   21) Method for manufacturing a metallized optical fiber made of silica or of silica containing a dopant, characterized in that it comprises the steps consisting in: * drawing an uncoated optical fiber (14) from a optical fiber preform (10) made of fused silica in a crucible (12), * regulating the diameter of the uncoated optical fiber (14) so that it has a given dimension, by means of a diameter measuring device ( 16), * passing the uncoated optical fiber (14) through a metallic coating device (18) containing molten tin, so as to form a layer of tin (42) of given thickness on the uncoated optical fiber (14),   * cool the optical fiber coated with tin in a device   cooling tif (26), and * winding the optical fiber coated with tin, by means of a   capstan (32), around a spool (34).   22) Method for manufacturing a metallized optical fiber according to claim 21, characterized in that   the temperature of the molten tin in the reflector   metallic clothing (18) is in the range of 231 C to 260 C.   23) Method for manufacturing a metallized optical fiber made of silica or of silica containing a dopant, characterized in that it comprises the steps consisting in: * drawing an uncoated optical fiber (14) from a optical fiber preform (10) made of fused silica in a crucible (12), * regulating the diameter of the uncoated optical fiber (14) so that it has a given dimension, by means of a diameter measuring device ( 16), * pass the uncoated optical fiber (14) through a metallic coating device (18) containing molten aluminum, so as to form an aluminum layer (44) of given thickness on the uncoated optical fiber (14),   * cool the aluminum coated optical fiber in a dis-   positive cooling (26), and * wind the aluminum coated optical fiber, by means of   a capstan (32), around a spool (34).   24) Method for manufacturing a metallized optical fiber according to claim 21, characterized in that   the temperature of the molten aluminum in the metal coating device (18) is in the range of 660 C to 690 C.